- Practical and Scalable Kinetic Resolution of BINOLs Mediated by a Chiral Counterion
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BINOLs are valuable and widely used building blocks, chiral ligands, and catalysts that are effective across a remarkable range of different chemical transformations. Here we demonstrate that an ammonium salt catalyzed kinetic resolution of racemic BINOLs with benzyl tosylate proceeds with s up to 46. This is a scalable and practical process that can be applied across >30 different C2- and non-C2-symmetric BINOLs. Implementation of this method enables the enantioselective synthesis of a wide range of BINOL derivatives with over 99:1 e.r.
- Jones, Benjamin A.,Balan, Tudor,Jolliffe, John D.,Campbell, Craig D.,Smith, Martin D.
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supporting information
p. 4596 - 4600
(2019/03/13)
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- Isothiourea-Catalysed Regioselective Acylative Kinetic Resolution of Axially Chiral Biaryl Diols
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An operationally simple isothiourea-catalysed acylative kinetic resolution of unprotected 1,1′-biaryl-2,2′-diol derivatives has been developed to allow access to axially chiral compounds in highly enantioenriched form (s values up to 190). Investigation of the reaction scope and limitations provided three key observations: i) the diol motif of the substrate was essential for good conversion and high s values; ii) the use of an α,α-disubstituted mixed anhydride (2,2-diphenylacetic pivalic anhydride) was critical to minimize diacylation and give high selectivity; iii) the presence of substituents in the 3,3′-positions of the diol hindered effective acylation. This final observation was exploited for the highly regioselective acylative kinetic resolution of unsymmetrical biaryl diol substrates bearing a single 3-substituent. Based on the key observations identified, acylation transition state models have been proposed to explain the atropselectivity of this kinetic resolution.
- Qu, Shen,Greenhalgh, Mark D.,Smith, Andrew D.
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supporting information
p. 2816 - 2823
(2019/02/05)
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- Preparative Resolution of Racemates on a Chiral Liquid Chromatography Column
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A 2 in. x 30 in. liquid chromatography column packed with a chiral stationary phase derived from (R)-phenylglycine has been found capable of resolving gram or larger samples of a variety of racemates.Nine such resolutions are presented.The racemates resol
- Pirkle, William H.,Finn, John M.
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p. 4037 - 4040
(2007/10/02)
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